The use of shaving aids on razor blades to provide lubrication benefits during the shave is known; see for example U.S. Pat. Nos. 7,121,754, 6,298,558, 5,711,076, 6,301,785, US2009/0223057 and US2006/0225285. Such shaving aids, typically called Lubrastrips, comprise a water-insoluble matrix material to provide structural integrity and a water-soluble polymer, such as polyethylene oxide, in order to provide lubrication during the shave once the water-soluble polymer forms a solution with the water present during shaving. Since the introduction of Lubrastrips, little development has been made in the field, even though these forms are not without limitations. For example, the polyethylene oxide lubricant can be perceived negatively by the consumer due to its inherent stringiness, the form and manufacturing process can degrade the polyethylene oxide efficacy and limit the inclusion of skin care actives and Lubrastrips are a hard non-compliant form that does not provide an appealing sensation on the skin.
Consequently, there is still a need to provide a shaving aid for razor cartridges exhibiting lubricating properties with the ability to contain and deliver a range of desirable skin actives in a controlled manner over multiple usage events, whilst also providing a differentiated and appealing visual and tactile aesthetics before and during use.
Surprisingly, it has been found that the provision of water soluble filaments on a razor cartridge, in a shaving aid for example, can provide these desired benefits. The filaments are preferably comprised of water soluble materials which act as both filament forming materials and lubricants whilst providing a desirable aesthetic before and during use. Optionally, the shaving aid may be coated or impregnated with skin care actives and/or laminated to further increase conformability and the perception of softness. Both the coating or impregnation and lamination also have the additional desired effect of controlling the rate of dissolution of the filaments and associated shaving aid in use.
Fibrous or filament forms are known for use on razor cartridges, as described for example in WO2013/096178. The fibres are described as resilient and non-water soluble and comprise a hydrophobic non-woven material including a polyamide or polyester. The function of the fibres is merely to act as an applicator and reservoir for shaving fluid dispensed into or onto the fibrous pad rather than any for an additional functional benefit. A problem with such resilient fibre or filament pads however is that the pads are prone to forming an undesirable appearance over use due to skin and hair debris collecting in the interstices.
The use of filament or fibrous substrates, often termed as non-woven substrates are described in consumer applications such as tissue towel and are characterized by a desirable cloth like feel and appearance. For example, US2013/0209272 describes a wet wipe comprising a non-woven substrate including polyvinylalcohol filaments or fibres and a surface treatment of hydrophilic material. Such webs can also be stacked or layered as described in WO20090022761 which describes stacking of dissolvable nano webs comprising fibres or filaments including starch and PVA. However, these webs have a high rate of dissolution and are not suitable for multiple usage. The use of filament forming materials that release actives in use are also described for example in US2012/0052036, US2012/0237576 and US2013/017142.
Very thin fibers have also been disclosed in other publications, see e.g., WO 2001026610, WO 2001051690, and U.S. Pat. Nos. 8,367,570 and 7,390,760. Despite these and other disclosures, there remains a need for innovation on the shaving aid space as conventional shaving aids can be limited in the amount or type of lubrication they provide and there can be a need for meaningful skin benefits which have not been offered in other shaving aids on the market.